You can only tell if it has activated by using specialised BMW equipment.

Indeed NFS.

Carloony, I hope you've been told about the BMW Alarm Recognition System.

Here's a shot of ARS headquarters, in Sevenoaks, Kent:

It simply lets the irritating alarm be remotely deactivated- you don't get told that the alarm has been activated in the first place- that's an extra £57.12 subscription, but you need to buy the BMW ARSphone so that they can ring you & tell you. Unsurprisingly, BMW charge £331 for that, without the SIM card.

The car comes with a free basic ARS subscription for the first year, but after that they could charge anything upto a hefty £373.91 for ongoing ARSing.

I really think you need to read your manual, Carlean-on-me, otherwise your dad may see some hefty payouts, without realising why.